Method for preparing reagent cobalt chloride hexahydrate

Abstract

The invention provides a method for preparing a reagent cobalt chloride hexahydrate. The method comprises the following steps of: reacting a metal cobalt slice with a concentrated nitric acid so as to generate a cobalt nitrate, directly reducing the cobalt nitrate by using formaldehyde in the condition of the esistence of hydrochloric acid so as to remove the nitrate radical to generate a cobalt chloride solution, filtering, concentrating and cool crystallizing so as to acquire the cobalt chloride hexahydrate. The method of the invention generates no other impurities except the target products, gas and water in the reaction process, and can obtain pure cobalt chloride hexahydrate. The products acquired by using the method meet the analytically pure standard of GB/T 1270-1996 chemical reagent cobalt chloride hexahydrate. The method has the advantages of simple operation, rapid reaction, short producing flow, high production efficiency, mild process condition, easily controlled property and application in mass commercial process.

Description

technical field [0001] The present invention relates to a preparation method of cobalt chloride, in particular to a preparation method of reagent grade cobalt chloride hexahydrate, and more specifically to a preparation method of reducing cobalt nitrate with formaldehyde to remove nitrate in the presence of hydrochloric acid to produce reagent grade hexahydrate A process for cobalt chloride hydrate. Background technique [0002] Cobalt chloride hexahydrate is a red monoclinic crystal, easy to deliquescence, with a melting point of 86-87°C, and loses all crystal water at 120-140°C to obtain blue anhydrous cobalt chloride. Soluble in water, soluble in ethanol, acetone, slightly soluble in ether. Cobalt chloride has a wide range of uses, mainly used as analytical reagent, humidity and moisture indicator, ceramic colorant, paint drier, catalyst and electroplating industry, etc. [0003] The usual preparation methods of cobalt chloride mainly include: (1) metal cobalt and hydro...

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Problems solved by technology

[0004] In the above-mentioned method, method (1) is because the reducibility of cobalt is relatively weak, and the replacement reaction with hydrogen ion is slow, needs relatively long time just could complete reaction, and reaction process produces flammable hydrogen, and there is safety problem in production process; Method ( 2) Since cobalt nitrate is converted to basic cobalt carbonate for precipitation, impurity entrainment and adsorption are easy to occur, it is difficult to wash and remove impurities, and the production process is relatively long, thus affecting product quality and production efficiency